This invention relates to vehicle air conditioning systems, and more particularly to over-the-road or off-road or off-road vehicle air conditioning systems and refrigeration systems.
Over-the-road or off-road vehicles, such as semi-tractor trailers and construction vehicles, are increasingly utilized to satisfy the transportation and construction needs of our economy. These increased needs result in increased utilization of these vehicles to the point where many are operated seven days a week and upwards of eighteen (18) to twenty (20) hours a day with a two person crew or multiple shift operations. This increased utilization is not simply a vehicle statement, but also includes a human factor as these vehicles are operated by at least a driver and often times by a driving team consisting of two individuals who share the duty of operating the vehicle. Since these vehicles are operated so extensively, increased driver and passenger comfort is essential, both in terms of environment temperature and physical space within the vehicle cab.
The need for environmental comfort during warm weather is satisfied through the use of an over-the-road or off-road vehicle air conditioning system, while the physical layout has been accommodated through new ergonomic interior designs, including reduced dash size, to maximize the available room within the vehicle cab for passenger occupation. Increased driver and passenger comfort may be further aided by the inclusion of a refrigerator or ice chest (cooler). Such devices are ideal for storing cold beverages and foods, or any other personal items which are desirably kept at low temperatures. This often allows a driver to remain on the road for longer periods of time between required stops for food and a cold drink.
Typical over-the-road or off-road vehicle air conditioning systems are of the compressor type. These air conditioning systems utilize a compressor, which is driven by a belt coupled to the engine to compress a refrigerant vapor under high pressure which is then circulated through a condenser to remove heat from the compressed high-pressure vapor and change it to a liquid state. The liquid refrigerant is then passed through an expansion valve which reduces the pressure on the refrigerant somewhat. This lower pressure refrigerant is then passed through an evaporator, which permits the return of the refrigerant to the vapor state, thereby removing heat from the air blown thereacross by an in-dash fan.
In a modern over-the-road or off-road vehicle, the main components of the refrigeration system, including the compressor and the condenser, are located remotely from the evaporator which is typically installed behind the dashboard air vents to provide cooling of the cabin air as described above, and from the condenser which is typically mounted with the vehicle radiator in the front of the engine compartment. Since the typical compressor vehicle air conditioning system is a closed loop system, the circulating high-pressure refrigerant must be passed from the remotely located components within the engine compartment to the vehicle cab-located evaporator and to the forward engine compartment, radiator located condenser via expensive high-pressure refrigeration hoses.
A typical installation includes the compressor and condenser in the engine compartment of the over-the-road or off-road vehicle, and utilizes multiple high-pressure refrigeration lines to couple these components through the firewall and into the cab behind the dash to the location of the evaporator, and to the radiator area of the engine compartment. Each of these high-pressure refrigeration lines require high-pressure couplings at each connection for the delivery and return of the high-pressure refrigerant in the air conditioning system.
As can well be imagined, both from the above-description as well as from personal experiences with vehicular air conditioning systems, this typical installation arrangement for an over-the-road or off-road vehicle air conditioning system is severely prone to leaks of the high-pressure refrigerant. These leaks occur at various locations, but are most frequent at the various couplings of the high-pressure hose which routes the high-pressure refrigerant from the condenser to the interior of the cab, under the dash, and to the location of the evaporator. Another frequent area for leaks occurs at the various couplings of the high-pressure hose which routes the high-pressure refrigerant from the compressor to the radiator area located condenser.
These leaks result in a reduced efficiency of the air conditioning system, expensive recharging of the system with new refrigerant, as well as a hazard to the environment through the escape of the refrigerant. An increased consciousness of the environmental impact that escaped refrigerant has on the planet, as well as increased government regulation regarding the inadvertent release of refrigeration refrigerant, has placed an increased emphasis on overcoming these problems.
In addition to the problem of leaks within the air conditioning system, the use of this type of system requires that expensive high-pressure refrigeration lines be utilized within the engine compartment, and between the engine compartment and the interior of the cab. In addition, expensive high-pressure couplings must also be utilized in an attempt to reduce the potential for leaks and catastrophic failure of the air conditioning system due to a failed connection of the high-pressure refrigeration lines. Also, because the refrigeration system is not closed until assembly of the vehicle takes place within the manufacturing assembly facility, the use of this type of system further burdens the assembly manufacturer by requiring that the initial purging and charging of the refrigeration system take place within the assembly plant of the vehicle itself. As mentioned above, since the use of refrigerant is a highly regulated process, requiring the manufacturing assembler to charge the refrigeration system greatly increases the cost associated with the manufacture of the vehicle.
In addition to:the problems associated with the typical air conditioning system just described, the inclusion of refrigerators or ice boxes (coolers) in the cab introduces additional problems. When coolers are used, the driver or passenger must purchase and partially fill the cooler with ice to keep the contents (food, drink, medicine, etc.) cool. Unfortunately, ice can only keep the contents cool for a relatively short period of time, as the ice will eventually melt. This melting is accelerated as the cover of the cooler is opened to gain access to the contents, as warm items are placed in the cooler, etc. As a result, the cooler tends to become filled with ice water, which causes many problems. Many coolers are prone to leaking the melted ice water. Further, emergency maneuvers may cause the cooler to shift and tip over, spilling the ice water and other content in the cab. These are obviously unwanted situations inside a vehicle. Further, the water from the melting ice often soaks the contents of the cooler. As a result certain products cannot be stored in the cooler without risking ruining them.
To overcome these drawbacks, vehicle refrigerators or cool boxes have been proposed. A common vehicle cool box is of the compressor type much like the aforementioned air conditioning systems. These cool boxes utilize a dedicated refrigeration circuit (separate from the air conditioning circuit discussed above) comprising a compressor, condenser, expansion valve and evaporator for the refrigerator. Therefore, when viewed from the overall vehicle level these systems require an additional compressor, an additional condenser, and additional expansion device, and an additional evaporator. Furthermore, since the compressor is driven by the engine and since the evaporator must be located within the cabin of the vehicle, these systems suffer the same drawbacks noted above with regard to air conditioning systems. Specifically, such systems require the same high-pressure couplings to route the refrigerant through the firewall, and therefore are prone to the same coolant leaks that pose such a problem. The use of a separate refrigerant circuit also reduces the overall efficiency of the vehicle, thus increasing the cost of ownership. Aftermarket installation of such systems is also quite expensive.
Portable electric powered refrigerators are one solution to the drawbacks of the current installed systems. However, these portable units are prone to tipping over in much the same way as the ice chests discussed above, and present much the same problem of where to put it in the cabin and still have room for the driver and co-driver or passenger. Also, the electric plug must typically be inserted in one of the available power points, such as the cigarette lighter, thus reducing the number of these that are available for required items. Further, the electric draw of such units can be substantial, especially when the vehicle is not running.
It is therefore an object of the invention to overcome many of these and other problems existing in the art. More specifically, it is an object of the instant invention to provide an over-the-road or off-road vehicle air conditioning system that has increased reliability and decreased impact to the environment. It is an additional object of the instant invention to provide an over-the-road or off-road vehicle air conditioning system that eliminates the necessity for evacuating and charging of the air conditioning system at the manufacturing assembly plant. Further, it is an object of the instant invention to provide an over-the-road or off-road vehicle air conditioning system which utilizes an in-vehicle heat exchanger with the cab air while eliminating the necessity for high-pressure refrigeration lines and high-pressure couplings running to and from the cab compartment. In one embodiment, the in-vehicle heat exchanger is located in-dash.
It is an additional object of the instant invention to provide an over-the-road or off-road vehicle air conditioning system that is modular in design, allowing for remote location of the main refrigeration circuit. It is an additional object of the instant invention to provide an over-the-road or off-road vehicle air conditioning system that allows for location of the main air conditioning circuit outside of the engine compartment in other more convenient locations.
It is a further object of the instant invention to eliminate the need for a separate refrigeration system for an on-board refrigerator or cool box and improve total system reliability. It is a related object to provide an on-board refrigerator or cool box that also eliminates the necessity for long high-pressure refrigeration lines running to and from the cabin area.
In view of these and other objects of the invention, it is a feature of the instant invention to provide an air conditioning system that utilizes a self-contained refrigeration system that is remotely located from the in-vehicle heat exchanger for the cabin air. It is a further feature of the instant invention that the remotely located self-contained portion of the air conditioning system contains all of the high-pressure system components in a closed system having permanent connections therebetween. It is an additional feature of the instant invention that the in-vehicle heat exchanger located within the cabin of the over-the-road or off-road vehicle contain a low-pressure refrigerant circuit which is utilized to cool the cabin air. It is a further feature of the instant invention that the low-pressure refrigerant circuit interfaces with the high-pressure, remotely located refrigerant system via a heat exchanger. Further, it is a feature of the instant invention that the air conditioning system also utilizes a low-pressure refrigerant circuit to remove heat from the compressed refrigerant in the high-pressure, remotely located self-contained modular circuit.
It is yet another feature of the instant invention to provide a low-pressure refrigerant circuit in communication with the evaporator having an on-board cool box that can be used alone or in conjunction with the in-vehicle heat exchanger.
In view of the above, an embodiment of the air conditioning system for an over-road or off-road vehicle having an engine located in an engine compartment and an occupant cabin, the occupant cabin having a dashboard including air flow vents and a vent fan included, the system of the present invention comprises a refrigeration power cell, a first heat exchanger adapted to be mounted in the dashboard of the occupant cabin, and a first low-pressure refrigerant communication circuit operably coupling the first heat exchanger to the refrigeration power cell.
In this system the refrigeration power cell comprises a high-pressure condenser-based refrigeration circuit. This circuit has a compressor, a condenser, an expansion device, and an evaporator. Also included is a circulation circuit which supplies low-pressure refrigerant to the low-pressure refrigerant communication circuit. The evaporator and the circulation circuit are in thermal communications whreby heat is removed from the low-pressure refrigerant. Preferably, the circulation circuit comprises a low-pressure refrigerant pump and an input and output low-pressure coupling. This pump circulates the low-pressure refrigerant though this heat exchanger across which the vent fan blows air to be cooled. This produces cooled air which flows through the vents and into the occupant cabin to cool same.
Preferably, the system of the present invention further comprises a second heat exchanger adapted to be mounted in the engine compartment, and a second low-pressure refrigerant communication circuit operably coupling this second heat exchanger to the refrigeration power cell. Additionally, the refrigeration power cell further comprises a second circulation circuit supplying a second low-pressure refrigerant to this second low-pressure refrigerant communication circuit. The condenser and this second circulation means are preferably in thermal communications whereby heat is removed from the refrigeration power cell by the second low-pressure refrigerant. In a system wherein the engine includes a radiator and an engine fan within the engine compartment, this second low-pressure refrigerant circulates through the second heat exchanger across which the engine fan draws air to remove heat from this second heat exchanger thereby cooling the second low-pressure refrigerant.
In an embodiment of the instant invention, the refrigeration power cell further comprises a sub-cooler thermally coupling the low temperature input of the compressor to the high temperature output of the compressor. This heat exchange increases the efficiency of the compressor. Additionally, the refrigeration power cell further comprises a drier interposed between the condenser and the expansion device. This drier removes water from the refrigeration circuit.
In an alternate embodiment of the instant invention, a modular air conditioning system comprises a self-contained refrigeration power cell, a heat exchanger remotely located from the refrigeration power cell, and a low-pressure refrigerant communication circuit. This low-pressure refrigerant communication circuit operably couples the refrigeration power cell to the heat exchanger, conveying low-pressure refrigerant therebetween. The refrigeration power cell comprises a compressor, a condenser, an expansion device, and an evaporator. The compressor, condenser, expansion device, and evaporator are serially coupled to form a high-pressure closed refrigeration circuit.
The refrigeration power cell further comprises a drive mechanism coupled to the compressor. This drive mechanism may be a hydraulic motor, an electric motor, or other appropriate device to allow remote operation from the engine compartment. Alternatively, the compressor may be belt driven in a conventional manner.
In an embodiment of the instant invention, the low-pressure refrigerant communication circuit thermally interfaces with the condenser to remove heat from the high-pressure closed refrigeration circuit. In this embodiment this heat exchanger is adapted to mount in proximity to a radiator in an engine compartment of an over-the-road or off-road vehicle.
Alternatively, the low-pressure refrigerant communication circuit thermally interfaces with the evaporator to remove heat from the low-pressure refrigerant. In this alternative embodiment the heat exchanger is adapted to mount under a dashboard of an over-the-road or off-road vehicle. Preferably, this embodiment of the instant invention further comprises a second heat exchanger remotely located from the refrigeration power cell, and a second low-pressure refrigerant communication circuit which is operably coupled to the refrigeration power cell and to the second heat exchanger for conveying second low-pressure refrigerant therebetween. In this embodiment the second low-pressure refrigerant communication circuit thermally interfaces with the condenser to remove heat from the high-pressure closed refrigeration circuit. Ideally, this second heat exchanger is adapted to mount in proximity to a radiator in an engine compartment of an over-the-road or off-road vehicle.
In yet another embodiment of the instant invention, a modular air conditioning and refrigeration system comprises a refrigeration power cell having a high-pressure condenser-based refrigeration circuit. This circuit has a compressor, a condenser, an expansion device and an evaporator. Also included is a low-pressure communication circuit having a low-pressure refrigerant. The evaporator and the low-pressure communication circuit are in thermal communication whereby heat is removed from the low-pressure refrigerant. The communication circuit includes a first heat exchanger and an onboard cool box. Preferably, a vent fan blows air to be cooled across the first heat exchanger that flows into the occupant cabin to cool the same. The heat exchanger and cool box are preferably coupled in parallel with appropriate valving such that low-pressure refrigerant can be supplied to the heat exchanger and cool box either individually or in combination.
These and other objects and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.